How can I add annotations to a heatmap in Matplotlib?

How can I add annotations to a heatmap in Matplotlib?

You can add annotations to a heatmap in Matplotlib using the text function. After creating your heatmap with imshow, you can loop through the data and use plt.text to place annotations.

Can you show me a code example for that?

Sure! Here's a simple example:

import matplotlib.pyplot as plt
import numpy as np

data = np.random.rand(10, 10)
plt.imshow(data, cmap='hot', interpolation='nearest')

for i in range(data.shape[0]):
    for j in range(data.shape[1]):
        plt.text(j, i, f'{data[i, j]:.2f}', ha='center', va='center', color='white')

plt.colorbar()
plt.show()

What do the parameters in plt.text mean?

In plt.text, the parameters are:

• x and y: the coordinates where the text will be placed.
• s: the string to be displayed.
• ha and va: horizontal and vertical alignment of the text.
• color: the color of the text.